This invention relates to electrostatographic reproduction apparatus such as copiers and printers, and more particularly to such a copier or printer that includes an imaging member having imaging and non-imaging portions and methods of use therewith.
Electrostatographic reproduction apparatus for producing copies of an original document are well known. Such copies typically are produced on suitable receiver sheets through a repeatable process that normally includes the steps of: (1) using electrostatic charges and first and/or second stations in some manner to form a latent image on the surface of an imaging or image-bearing member; (2) developing the latent image at a third station with developer material that includes toner particles; (3) transferring the developed image at a fourth station from the imaging member to a suitable receiver sheet for subsequent fusing; and (4) cleaning the image-bearing surface of the imaging member thereafter at a fifth station by removing residual toner and other particles therefrom.
In such reproduction apparatus in which the imaging member is repeatedly reused, ordinarily the imaging member has an endless shape for example in the form of a drum or of a flexible web. The endless flexible web form has certain advantages and disadvantages relative to the drum form. Among the advantages is the fact that such a flexible web can be disposed in a flat orientation along one portion thereof, and in a curved orientation along another portion thereby facilitating placement of operating stations thereabout. More importantly, the flexible web form of an imaging member can allow for multiple images to be in the formation process at any given time and still retain some compactness and overall machine size.
Among the disadvantages, however, is the presence of a web splice or seam that is where two ends of the web material usually have been splice-joined together in order to form its endless shape. Unfortunately, the portion of the web including an area immediately adjacent to either side of the splice may be not suitable for forming quality images, and so is regarded as a non-imaging area. Accordingly, in order to avoid forming images on such a non-imaging area, it is conventional to move the web about its path in the reproduction apparatus until the splice is detected by a detector located at a fixed location selected so that the imaging portion of the web is then in a position to run in proper registration with the fixed electrostatographic process stations of the apparatus as described above. The splice may be detected by the detector by providing on the web adjacent to the splice area a permanent mark or indicium such as a perforation or patch of density that can be detected by the detector.
In U.S. application Ser. No. 08/841,008, filed on Apr. 29, 1997, in the names of Ziegelmuller et al, there is disclosed an electrophotographic recording apparatus wherein contamination of the transfer roller is reduced. The transfer roller is normally electrically biased to attract toner particles forming an image on a photoconductive web or belt. The electrical voltage bias or potential on the transfer roller is such as to attract the electrostatically charged toner particles forming the developed image to the receiver sheet which is advanced into a nip formed between the photoconductive web or belt and the transfer roller. In order to control process setpoints for the various electrophotographic operating stations, it is desirable to record process control patches and develop the patches with toner particles. It is not usually desirable to transfer these patches to a receiver sheet, so the patches are typically measured for density and then removed from the photoconductive belt. In order to maintain productivity of the machine, it is desirable to form the process control patches in areas of the belt not overlapping with image areas so that the image areas can be used for recording images.
A problem with operating a photoconductive web at high speed is that in order to minimize contamination of the transfer roller when engaging a process control patch or area that tends to collect toner, such as a seam, it is desirable to reverse bias the transfer roller so that the roller tends to repel the charge on the toner particles and thereby avoids attracting the toner particles from the patch or the seam onto the transfer roller.
Just after cycle-up of the copier/printer from say an off or rest condition where the photoconductive member is stationary, an image transfer operation may be scheduled at any available image frame. However, the inventors have noted image artifacts can occur with the first image of a production run just after cycle-up. It is, therefore, an object of the invention to overcome the noted problem.
The above and other objects and advantages will become more apparent upon reading of a detailed description of the preferred embodiments of the invention provided below.
In accordance with the present invention there is provided an electrostatographic recording apparatus comprising a primary image forming member (PIFM) moving along a closed path, the PIFM being sufficiently large to form a series of images thereon in the direction of movement of the PIFM during a production run of image formation, a toner image recorder that forms plural series of toner images on the PIFM during production runs, toner images of the plural series of toner images normally being formed at a first location on the PIFM which is adjacent to and downstream of, in the direction of movement of the PIFM, a second location that is not used for image recording of production images during the production runs, a transfer device in engagement with the PIFM for transferring the toner images from the PIFM, a source of electrical bias for electrically biasing the transfer device to a voltage of a first polarity when transferring the toner images from the PIFM and for electrically biasing the transfer device to a voltage of a second polarity that is of a polarity that is opposite to the polarity of the first polarity at the second location on the PIFM during production runs when the transfer device is not transferring toner images from the PIFM, a controller for controlling the source for signaling the source to switch from the one polarity to the second polarity, and the controller being programmed to control the toner image recorder by providing, after a new cycle-up of the apparatus, for no recording at the first location on the PIFM of a first image forming a part of a new production run of images and instead recording the first image at a next available location on the PIFM downstream of the first location in the direction of movement of the PIFM.
In accordance with a second aspect of the invention, there is provided a method of recording with an electrostatographic recording apparatus, which comprises the movement of a primary image forming member (PIFM) along a closed path, the PIFM being sufficiently large to form a series of images thereon in the direction of movement of the PIFM during a production run of image formation, forming plural series of toner images on the PIFM during production runs, a first location on the PIFM being normally used to form images forming a part of the production runs, the first location being adjacent to and downstream of, in the direction of movement of the PIFM, a second location that is not used for image recording of production images during the production runs, electrically biasing a transfer device that is in engagement with the PIFM to a voltage of a first polarity when transferring toner images from the PIFM and electrically biasing the transfer device to a voltage of a second polarity that is a polarity that is of opposite polarity to the first polarity when the transfer device is in engagement with the PIFM at the second location, and providing, after a new cycle-up of the apparatus, for no recording at the first location on the PIFM of a first image forming a part of a new production run of images and instead recording the first image at a next available location on the PIFM downstream of the first location in the direction of movement of the PIFM, so that the transfer device is provided more time to recover when switching from the second polarity to the first polarity.